Diblock Copolymer Melts of Linear Chains, Rings and Trefoil Knots in Lamellar Morphology: A Molecular Dynamics Simulations Study

We present results of coarse-grained molecular dynamics simulations of phase separating diblock copolymer melts having different chain topologies. Specifically, we investigated the self-assembly of 50-50 AB lamella structures composed of linear chains, rings or trefoil knots having the same molecular weights. The lamellar-disordered phase transition stays first order, while the order-disorder temperature (ODT) and the domain sizes, both, follow the sequence: linear chains > rings > trefoil knots. This behavior correlates with the size of the polymer chain in the disordered and ordered (lamellar) melts. Investigation of the polymer chain structures shows that chains are perturbed relative to the homopolymer melt with structures being stretched and compressed in the normal and lateral dimensions of the lamella domains, respectively.